Compounds incorporating the general structure of an S- alkylisothiazolidine ring, will be synthesized by oxidizing S-alkylated derivatives of 3-mercaptopropylamine according to the general procedures outlined by Lavine (Lavine, T.F., U.S. Patent No. 2,465,461, March 29, 1949). The main compound of interest is derived from methionine and was given the trivial name of dehydromethionine by Lavine (a more descriptive name is 1-methyl-isothiazolidine-3-carboxylate). The structure of dehydromethionine proposed by Lavine will be confirmed by using the standard methods of organic chemistry including spectroscopy (especially NMR), elemental analysis, and tests for the presence of characteristic functional groups. The chemical properties of the S-alkylisothiazolidines will be explored with the prime goal being to determine the possible role of these compounds in biological systems. Specifically, their thermal stability, and their reactions toward acids, bases, nucleophiles, electrophiles, oxidizing agents, and reducing agents (especially thiols) will be studied. Novel rearrangements of the ring may occur, and there is the possibility of alkyl transfer from the sulfonium pole. Both aqueous and non-aqueous solvents will be employed. Preliminary data indicates that dehydromethionine will react with orthophosphate in a non-aqueous solvent to produce a phosphorylating intermediate. Thus, a model system for oxidative phosphorylation can be constructed in which oxidation of methionine by iodine gives an isolable, non-phosphorylated, high-energy intermediate.